Creates an Expr by reading it off a link.
The created Expr
This factory method will only be used by advanced programmers who are creating their own classes that implement the IMathLink interface. You would call this method in your implementation of GetExpr. In other words, this method exists not as a means for casual users to create Exprs from a link (use the GetExpr method instead), but so that IMathLink implementors can write their own GetExpr methods without having to know anything about the internals of the Expr class. Exprs know how to read themselves off a link.
|MathLinkException||On any MathLink error.|